A considerable amount of power in the form of internal combustion engines is installed on large, sea-going marine vessels. This not only includes navy marine vessels such as frigates and corvettes, etc. or large yachts, but also includes ferries, etc. These internal combustion engines produce a considerable amount of exhaust gas which is blown into the atmosphere. Not only in the case of merchant marine vessels but also in many navy marine vessels, this is generally done upwards and leads to a not inconsiderable disturbing exhaust gas plume. This can be seen for miles across the sea, and can even be detected by infrared beyond the radar horizon (location).
In order to reduce the visual impact and the capability to locate the exhaust gas plume or to avoid this, some navy marine vessels normally emit the exhaust gases slightly above the waterline, for example at the side, or slightly below the waterline, and in this case preferably at the stern. However, even the latter measure does not lead to sufficiently good mixing of the exhaust gases with the water that it would not be possible to locate the exhaust gases as they rise from the gas bubbles that are formed.